Snap switch for direct current



g 1958 KAZUMA TATElSHI 2,849,580

SNAP SWITCH FOR DIRECT CURRENT Filed April 7, 1954 INVENTOR )fagzzma.Z'afez'shi United States This invention relates to a snap switch fordirect current.

It is an object of the invention to provide a switch of compact formespecially adapted to be used for controlling direct current.

It is another object to construct a snap switch which can handlerelatively large amount of direct current with safety.

A still further object of this invention is to protect the inner wallsof the switch casing from high temperature of arcs.

The invention is illustrated in the accompanying drawings, in which:

Fig. l is a side sectional view of the snap switch according to thisinvention,

Fig. 2 is a plan view of the casing with the cover removed, and

Fig. 3 is the sectional view taken on line III-III of Fig. 2.

In said drawings, 2 is a casing of any suitable insulating materialwherein a leaf spring 6 carrying contacts 7 and 7' at one end, is fixedat the other end by a screw 4 to an anchor 3. Said leaf spring 6constitutes the central arm of a three-armed spring plate 13, the tworemaining arms of which consisting of the compression spring members 6.Said spring members 6' are thus preferably formed as an integral part ofthe plate 13 and are integral with the leaf spring 6. The spring members6' are shorter than the leaf spring 6 and are maintained in compressionby being bowed downwardly as clearly shown in Fig. 1 by having theirends disposed in the notches 5 in the anchor 3.

Further, in the casing 2, an upper stationary contact 8 and a lowerstationary contact 8 are so arranged at the opposite sides of the anchor3 as to make contact with the contacts 7 and 7 respectively which arefixed at the end of the leaf spring 6.

1 is a cover in which a small permanent magnet block 9 is partiallyembedded just above the stationary contacts 3 and 8'.

Between the cover 1 and the casing 2, a push button 11 is placed withits plunger 12 protruding upwardly from the cover 1 while its lowest endrests on the leaf spring 6.

The drawings show the switch in its normal state wherein the contact 7is in contact with the upper stationary contact 8 while the lowerstationary contact 8 remains opened.

When the plunger 12 is depressed, the leaf spring 6 bends downwardlyagainst the action of the compression members 6' until the dead point ofthe link is over when the contact between the contacts 7 and 8 is openedand the contact between the contacts 7 and 8 is closed quickly by thesnap action of the spring plate 13. When the plunger 12 is released, thespring plate 1.3 snaps back quickly with the aid of the compressionmembers 6' as well as the elasticity of the leaf spring 6, and thecontact between the contacts 7' and 8' is opened and the contact betweenthe contacts 7 and 8 is reestablished. The arcs generated between themoving contacts 7, 7' and stationary contacts 8, 8 during the opening ofthe circuits are both blown sidewards by the magnetic flux of the magnet9 as it is arranged horizontally with longitilt 2 tudinal poles andquenched so quickly that the contacts are protected from burning out dueto the immense heat of the arcs. Consequently, the switch becomescapable of handling relatively large amount of direct current safely.

In the switch shown here, as the magnet 9 is arranged horizontally withlongitudinal poles, the arcs produced at the upper and lower stationarycontacts are blown sidewards against the inner walls of the casing 2where sheets 10 of metal with good heat conductivity such as copper andbrass are attached to cool the heat of the are by distributing itquickly and evenly over the surfaces of said sheets when the arc reachesto them, whereby the breaking capacity of the direct current of thisimproved switch is adequately increased and moreover the walls of thecasing 2 are effectively protected from the are.

To increase the cooling effect of the sheets 10, it is preferable toprovide openings 14 in the casing 2 just behind said sheets.

In the present invention, as a small rectangular block of permanentmagnet is used, the size of the whole switch can be made smaller thanthe switch which uses a horse shoe magnet.

It is further to be noted that the arrangement of the permanent magnet 9wherein the line connecting the poles is longitudinal to the leaf spring6, is one of the important features of the invention; because, if saidmagnet be placed with the line connecting the poles be vertical to theleaf spring, the arc will be blown along and onto the leaf springwhereby the quenching of the are will become difficult and thecapability of the switch for cutting off direct current will be muchreduced.

Having described my invention, I now claim:

A double-throw snap switch for direct current comprising a completelyclosed casing, an anchor mounted therein and having a notched end, athree-armed spring plate having a central spring arm secured at one endto the anchor, contacts carried by and movable with the other end of thespring arm, the two remaining arms of the plate being bowed undercompression and maintained in such bowed condition by engagement withthe notched end of the anchor, upper and lower stationary contactsmounted within the casing respectively above and below thecontactcarrying end of the spring arm, a cover fitted on and closing thecasing, a push button having a plunger operative through the cover andlocated above the spring arm and adapted when depressed to force thespring arm downwardly, a permanent magnet partially embedded in andcarried by the cover and positioned above the upper stationary contactwith its poles disposed longitudinally to the spring arm, whereby an areformed upon breaking of contacts is deflected transversely of said armand sheets of heat-oonductive metal attached to the inner side wallsurfaces of the casing adjacent to the contacts in the path of arcdeflection, the walls of the casing overlying said sheets' beingperforated for heat transfer directly to the atmosphere.

References Cited in the file of this patent UNITED STATES PATENTS1,146,637 Massa A July 13, 1915 1,960,020 McGall May 22, 1934 2,096,502Wetzel Oct. 19, 1937 2,133,158 Planck et al Oct. 11, 1938 2,250,016Garner July 22, 1941 2,374,986 Fetter May 1, 1945 2,380,851 Lamb July31, 1945 2,417,134 Scott Mar. 11, 1947 2,490,020 Enzler Dec. 6, 19492,627,754 Millard Feb. 10, 1953 2,639,352 Watson May 19, 1953

